A must have is something that one cannot, or at least should not go without. Several years ago, the Birkin bag was a must have for women. Actually, it was a must have that many women couldn’t have because it was simply unaffordable for most women. For men, especially athletes, a must have item can be a certain brand of sneakers, or a new stylish gadget for home or one’s car. On a visceral level, a must have item is something that a person feels they want so badly that they actually need it.
Basketball players or urban kids may have “Air Jordans” as a must have. These days, a IPad is a “must have” in the technology industry.
A must have is a hot fashion item that has been accepted by the mainstream fashion industry for a particular season or longer time frame.